SLI with no bridge, different cards, non-SLI mobo

[britain4]

Been running in SLI with no bridge today due to having fitted a second card but can't find the bridge that came with my mobo so waiting on one from China lol

Used DifferentSLIAuto to make it possible. Surprisingly it's given a 50-60% boost in games and benchmarks which I didn't think would be possible without a bridge. Also both GPUs are seeing around 95% usage but I don't know how that is affected by the bridge not being present if at all.

Should be noted that this can also (as the name suggests) be used to make different but similar Nvidia cards SLI and it can also be used to SLI on boards that don’t support it. As long as the VRAM is the same, someone did a 1070 and a 980 ti with it, a 570 and a 580 etc etc. Also cards with no SLI support built in like a 1060. Important to read through the thread before trying it, I had to roll my drivers back to October 2017 or something to get support for the latest version, you will also need to activate test signing mode in Windows to get the hacked driver to load.

I am expecting improvements when I do fit the bridge but this will certainly tide me over until it arrives. Had no idea this was possible until today! Can't imagine it will be of any use for a lot of people but I am enjoying a taste of my new SLI setup a little earlier than I would have been otherwise.

Anyway just thought I’d post about my experience with it, thought it was cool.

 

[Quartz]

Paging @Kaapstad to test with his two Titan V cards.

 

[britain4]

Would be interesting to see how it worked for higher end cards. It certainly works with no bridge so could be used to SLI cards that aren’t designed for it like a 1060 or probably a 1050 ti with little or no restriction to bandwidth

 

[VincentHanna]

Asynchronous multi GPU is a feature of DX12 but very few game support it.

Anyway certain games can even run with one Nvidia card and one AMD card

 

[tictaktoe333]

I didn't know that SLI without a bridge was a thing apart from that DX12 thing which nothing supports.. However that is like cross-platform SLI as you can have any cards together that support it!

 

[britain4]

Asynchronous multi GPU is a feature of DX12 but very few game support it.

Anyway certain games can even run with one Nvidia card and one AMD card

Yeah this is true. Not very well supported but it can be done.

I didn't know that SLI without a bridge was a thing apart from that DX12 thing which nothing supports.. However that is like cross-platform SLI as you can have any cards together that support it!

It would be cool if they developed it further in the future! For now though I think it’s a very cool hack. Definitely is a hack but gets the job done. Considering the fuss over HB vs normal bridge the scaling is crazy (although the impact supposedly gets more severe as the cards get faster)

 

[Silent_Scone]

I didn't know that SLI without a bridge was a thing apart from that DX12 thing which nothing supports.. However that is like cross-platform SLI as you can have any cards together that support it!

It's not really a thing. The bridge actually does very little. But without the data that conventionally passes across it I'm sure what you could expect in terms of performance. Pacing issues, for one.

 

[tictaktoe333]

Yeah this is true. Not very well supported but it can be done.

It would be cool if they developed it further in the future! For now though I think it’s a very cool hack. Definitely is a hack but gets the job done. Considering the fuss over HB vs normal bridge the scaling is crazy (although the impact gets much more severe as the cards get faster)

Yeah its really cool!! It kinda stops brand differentiation to some degree. So if every game supported it I am unsure whether that would be a positive or negative thing for the market tbh. AMD and Nvidia are always going to want multiple GPU protocols to favour the strongest performance being with their own cards to drive excess sales - So I wouldn't be surprised if nvidia find some way of making sure it never gets fully developed. That said, I am green team - but their business practises are ***** (technical term coming from someone with a business degree) haha

Paging @Kaapstad to test with his two Titan V cards.

Now this I really want to see!

It's not really a thing. The bridge actually does very little. But without the data that conventionally passes across it I'm sure what you could expect in terms of performance. Pacing issues, for one.

Yeah I guessed the bridge itself was an external timing method - still don't understand the really "necessary" need for high bandwidth though. Personally I think the high-brandwidth SLI bridge thing was more of a marketing ploy than technical innovation!

 

[britain4]

It's not really a thing. The bridge actually does very little. But without the data that conventionally passes across it I'm sure what you could expect in terms of performance. Pacing issues, for one.

No not really a thing as making it work requires a reasonably messy hack. I get butter smooth gameplay on it at the moment so I too am unsure what differences to expect from fitting the bridge. From what I can gather the data passes through the PCIE bus instead so will probably just be a little slower. From some googling it seems like older Nvidia drivers did allow it which is interesting

Yeah its really cool!! It kinda stops brand differentiation to some degree. So if every game supported it I am unsure whether that would be a positive or negative thing for the market tbh. AMD and Nvidia are always going to want multiple GPU protocols to favour the strongest performance being with their own cards to drive excess sales - So I wouldn't be surprised if nvidia find some way of making sure it never gets fully developed. That said, I am green team - but their business practises are ***** (technical term coming from someone with a business degree) haha


Now this I really want to see!


Yeah I guessed the bridge itself was an external timing method - still don't understand the really "necessary" need for high bandwidth though. Personally I think the high-brandwidth SLI bridge thing was more of a marketing ploy than technical innovation!

I think it would be a positive thing - if someone buys a card now to SLI later they will have to buy used anyway. So makes no difference to AMD or Nvidia which one they go for. I can’t see anyone specifically buying two cards of different brands to go together - just if they have one lying round or have upgraded to the “other side” anyway.

 

[Silent_Scone]

No not really a thing as making it work requires a reasonably messy hack. I get butter smooth gameplay on it at the moment so I too am unsure what differences to expect from fitting the bridge. From what I can gather the data passes through the PCIE bus instead so will probably just be a little slower. From some googling it seems like older Nvidia drivers did allow it which is interesting

Is it butter smooth, though? You'd need to see some frame pacing data. The trouble is, without the bridge, that data has nowhere to go other than the PCIE bus. There's a reason NVIDIA still use this method for AFR, but given the current state of things it's a legacy issue. SLI is dead in my opinion.

 

[jigger]

Is it butter smooth, though? You'd need to see some frame pacing data. The trouble is, without the bridge, that data has nowhere to go other than the PCIE bus. There's a reason NVIDIA still use this method for AFR, but given the current state of things it's a legacy issue. SLI is dead in my opinion.

Why would you need frame pacing data to tell if the game play is smooth... If the game play is smooth then it's smooth.

 

[britain4]

Well OK then it’s butter smooth in all games as far as I can see - but I’m not one of those people who can tell minute amounts of stutter or 60fps vs 144 etc.

In games like Witcher 3 that more or less maxes out both cards (with every setting cranked up) and in games that run at 60fps just the same on 1 card.

 

[Silent_Scone]

Why would you need frame pacing data to tell if the game play is smooth... If the game play is smooth then it's smooth.

Of course, not subjective at all is it? Why would you need a thermometer to tell you your temperature when you can use the back of your hand?
/S

Back in your box

 

[jigger]

Well OK then it’s butter smooth in all games as far as I can see - but I’m not one of those people who can tell minute amounts of stutter or 60fps vs 144 etc.

In games like Witcher 3 that more or less maxes out both cards (with every setting cranked up) and in games that run at 60fps just the same on 1 card.

Ah you mean you're like 99% of the population.

 

[jigger]

Of course, not subjective at all is it? Why would you need a thermometer to tell you your temperature when you can use the back of your hand?
/S

Back in your box

Not sure why you would use the word subjective.... Are you saying in your opinion the games aren't smooth now?

 

[Phixsator]

Ah you mean you're like 99% of the population.

Wee im special!!!!

 

[britain4]

I am a little confused lol, of course it’s subjective whether or not a game is running smoothly. You can't quantify smoothness, someone might say 30fps is smooth and some might (do) say 144fps or it's lagging

Anyway I'll be sure to update the results once the bridge does come on the slow boat from China. Initial benchmark results are very encouraging - 5029 points in Valley at 1080p Extreme, 2912 in Heaven 1080p Extreme. Can't do Superposition as the drivers I'm on have no profile for it

 

[Silent_Scone]

Not sure why you would use the word subjective.... Are you saying in your opinion the games aren't smooth now?

So something that's perceived by the eye isn't subjective? The affects of latency in different genres isn't subjective? Are you sure you want to go down that road?

Why ever bother showing frametime analysis if that's the case. The media has been doing it wrong all this time. Very strange.

The fact is, NVIDIA use the bridge for synchronisation and the little data that's passed is namely for that purpose, and to avoid conflicting with traffic passed through the PCIE bus. With the bridge removed, I'd want to see just how smooth that is. Not everyone is happy with pseudoscience science.

 

[britain4]

Well I’ve never had anything arrive so quickly from China before and so this evening I have been conducting some very basic and un-scientific tests to determine more definitively what the effect of running without the bridge is.

Valley benchmark 1080p Extreme score is up to 5342 from 5029 with no bridge, from 3223 on a single card. Heaven 1080p Extreme up from 2912 to 3266, from 1728 on a single card.

Frame times in GTA 5 are a bit all over the place with no bridge there -

But with the bridge in place they are a lot more stable (few spikes here and there due to texture streaming from a spinning disk)

I honestly can’t tell any visual differences between the two though in terms of “smoothness”. Perhaps someone with a more trained eye could.

If you have a decent board there is no reason you couldn’t SLI 2 un-SLIable cards using this method as it has a relatively small impact to performance. 2 1050 ti’s would probably work perfectly. Of course with a 980ti and a 1070 for instance you can connect the bridge as normal.